Jose Federico de Carvajal, president of the Spanish Senate, asked about Dr. Sakharov in Moscow on Sunday morning at the end of an official one-week visit to the Soviet Union. ''High-ranking Soviet authorities assured me he was alive and it was obvious that they had made prior consultations before releasing this information,'' he added.

The Times (London) backed off Monday from a report in the Sunday Times that Sakharov had passed on, quoting unidentified Western diplomats in Moscow as saying Sakharov was alive.